Toward an FBG Interrogation Scheme for Temperature Measurement Based on Gaussian Optical Source

Fiber Bragg Grating (FBG) techniques excel in detecting strains and temperature changes. Their versatility for direct measurements in dedicated environments and widespread use in fiber optic sensors make them pivotal. Recent studies emphasize real-time spectrum measurements, using FBG's Bragg wavelength shifts to deduce temperature fluctuations. Transitioning to a “system-embedded” interrogation technique and a spectrometer-free approach, this paper introduces a temperature interrogation method inspired by edge detection. The proposed approach utilizes a Gaussian optical source, replacing a broad-band one, to circumvent the costly implementation of optical edge filters for detection. It translates the FBG's shift into a simple intensity measurement for temperature variation. A collimated laser diode (LD) with a maximum power of 7 mW interrogates our near-infrared FBG, where both of them operate at a wave-length of 784.39 nm. The experimental setup involves a heating procedure to vary the temperature from 25°C to 70°C, testing the proposed approach. Results demonstrate a linear relationship between temperature variation and photodiode output power, highlighting the potential system integration of this approach for temperature monitoring.